This invention relates to a method of and apparatus for handling and separating limp fabric pieces and in particular to an apparatus which may be used in manual pickup operations or in combination with a pick-up device of the type described in my prior U.S. Pat. No. 4,009,786 or other similar devices adapted to feed, transfer and stack limp fabric work pieces to and through automatic or semiautomatic process machines such as, for example, garment processing machines.
The manufacture of clothing and other products from cloth or like flexible sheet material can be achieved by sewing and other processes applied to pre-cut work pieces usually delivered in stacks to the processing machines. The manufacture of other articles such as drapery, footwear, soft furnishings, auto seat covers and trims, and the like can also be achieved from assemblies of sewn or bonded pieces cut from webs of material. Normally, the productivity of the industries manufacturing these products is limited by the ability of operators to pick up and gain control of the individual pieces and present them in matched assemblies to adjustable process machines.
Process machines are available which are designed to perform particular operational functions such as control of the direction of sewing, positioning of work pieces, machine stop/start and other known desired functions in the manufacture of an article from fabric or like flexible material.
In order to feed these sewing and other machines, various devices have been proposed with the object of gaining control of the material and separating individual pieces from a cut stack of pieces. In the past, methods of operation used for feeding such machines have met with varying degrees of success due to the porosity and handling variables of the material and the comparative limp nature of fabric materials, and difficulties of separation from following pieces in a stack presents additional problems.
Apart from the device of my prior U.S. Pat. No. 4,009,786, a number of devices have been designed in an attempt to solve fabric feeding problems. One type of known device relies upon adhesion to a sticky surface; another utilized inwardly closing prongs in the manner of a chuck; another uses high frictional surfaces to pinch the surface ply; another uses the uniformly angularly oriented needles of card cloth for unidirectional frictional contact and pickoff; and yet another uses air suction members. Having gained control of the top piece of cloth, various means have been used to separate the piece without displacement of the other pieces in a stack, since any such movement would spoil the accuracy of engagement of the subsequent pieces and thus positioning would be inaccurate.
These devices have proved successful with a limited range of fabrics but have not solved the problems associated with the separation of woven or knitted cloth work pieces wherein the hairy surfaces of such cloths entangle and form a strong bond between pairs of plies in a stack. This is particularly so in the case of circular knit tubular cloths and in other cases edge threads become entangled or thermoplastic yarns may be fused together when the fabric pieces are cut from a stack.
Unsuccessful attempts have been made to overcome the above-atated problems including the application of suction to the stack or the engaging and lifting of an edge of the top ply and the insertion of a thin rigid plate which latter method is not reliable as plies bonded in pairs present an unsupported ply which distorts and is not accessible.
It is an object of the invention to provide positive effective means to firstly separate strongly bonded plies in a stack, even when bonded in pairs, then firmly grip the second ply of the stack and thereafter positively engage the top ply and peel it from the second retained ply.
A further object of the invention is to provide a method and apparatus which maintains control of a stack of plies so as to prevent the stack from "walking" or being displaced during the fabric separating and feeding cycles.
Yet another object of the invention is to retain the cut portions of the top plies as the deep soft stacks are mechanically elevated during the feeding process. It has been found that maintaining stack alignment is a major problem when working with very soft limp materials in economically viable deep stacks.